1. Field of the Invention
The present invention relates to a method and an apparatus for compensating for an interlaced-scan type video signal, and more particularly to a method and an apparatus for compensating for an interlaced-scan type video signal, in which interlaced-scan type data for a CRT are divided into two groups supplied into first and second fields, respectively, while artificially complementing shortage of data in first and second fields, thereby displaying the interlaced-scan type video signal in a liquid crystal display (LCD) panel.
2. Description of the Prior Art
According to conventional CRT type display methods, images are displayed by using 525 data lines in countries adopting NTSC (national television standard committee), or displayed by using 625 data lines in countries adopting PAL (phase alternation by line) based on an interlaced scan technique.
Such an interlaced scan technique is adapted for characteristics of a CRT. The term “interlaced scan” refers a scanning technique in which an electron gun slantingly scans data lines of a screen on every other data line, and then, scans remaining data lines in a next stage. FIG. 1 is a view showing a conventional interlaced scan. FIG. 2 is a view showing a display method of an LCD by using a conventional interlaced scan. FIG. 3 is a view showing a first data field for a conventional interlaced scan. FIG. 4 is a view showing a second data field for a conventional interlaced scan. Since the interlaced scan technique may slantingly scan data lines on every other data line, it is impossible to completely scan first and final data lines from one end to other end of a screen. For this reason, only half of the first data line and half of the final data are provided in order to compensate for ends of the screen. Thus, image data for the CRT cannot be divided by two due to the half-data for the first and final data lines, that is, the total number of the data lines is an odd number.
However, the above-mentioned interlaced scan may not be directly applied to an LCD. That is, the data scanning cannot be slantingly carried out in the LCD. Different from the CRT, which forms one frame by combining two fields, the LCD may form one frame by using one field. Therefore, if interlaced scan type data are directly applied to the LCD, only a half of data is provided for a first data line of a first frame and only a half of data is provided for a final data line of a next frame. Accordingly, since the first line of the first frame has half-data and the first line of the next frame has full-data, when data of the first and next frames are simultaneously displayed, the data in the first line may represent an image, which does not reflect data for the first line of the first frame or data for the first line of the next frame. Similarly, data in the final data line may represent an image, which does not reflect data for the final line of the first frame or data for the final line of the next frame when data of the first and next frames are simultaneously displayed. Such a problem may cause a reduction of a viewing area when displaying an image, so 234 lines in EGA-level resolution of 312*234 may be fixed.